Abstract
Variable air volume (VAV) is the most common installation among heating ventilating and air conditioning (HVAC) systems. To maintain the comfort level and lessen energy utilization, there is a pressing need for its effective control. In this study, a lumped parameter model composed of multizone VAV is considered, and sliding mode control (SMC) is designed to guarantee robust operation in the presence of uncertainties. For comparison of the proposed controller performance, a proportional integral derivative (PID) controller is additionally designed. The indoor temperature of zones is controlled by positioning the supply air dampers. Tracking objectives of controllers are inspected via two practical cases of desired temperature setpoints including (a) sinusoidal waveform and (b) the combination of steps. Results obtained using SMC ensure the robust operation of the VAV system against parametric uncertainties. In addition, SMC is more energy efficient than PID in terms of overshoot and settling time.
Highlights
Social expectations for the betterment of life standards lead to widespread use of air conditioners in buildings to improve the comfort level for occupants
Researchers have carried out a large number of research works to reduce the energy consumption of heating ventilation and air conditioning (HVAC) while maintaining Indoor air quality (IAQ) and comfort level
It is obvious that the proportional integral derivative (PID) shows more overshoot in the beginning and does not completely track the setpoint; whereas, sliding mode control (SMC) is tracking the setpoint effectively with negligible overshoot and the steady state
Summary
Social expectations for the betterment of life standards lead to widespread use of air conditioners in buildings to improve the comfort level for occupants. The authors in [9] discussed a variable refrigerant flow (VRF) and VAV air conditioning combined control system approach. For this type of combined system, an online optimal control is presented. A control technique to lower the air flow rate in the VAV terminal unit for an office building was presented in [15]. The authors in [23] discussed an MPC-based nonlinear control of an air conditioning system for an office in building. The contribution of this paper is that a lumped parameter type nonlinear model of a VAV air conditioning system is examined within the sight of practical harmonic unsettling influences in dynamic state variables.
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